Amphibious armor

ABSTRACT

Buoyant armor for jacketed rounds includes an outer, laminate reinforced strike face having a hardness greater than 640 Brinell. The strike face is configured to strip the jacket off a projectile as it passes through the strike face and to rotate the projectile. An inner, laminate reinforced strike face is separated from the outer, laminate reinforced strike face by a spacer layer. Foam greater than 40 mm thick is disposed behind the inner strike face and is configured to disperse a round and/or its fragments and to provide buoyancy to the armor.

FIELD OF THE INVENTION

The subject invention relates to armor.

BACKGROUND OF THE INVENTION

Buoyant armor typically includes a metal outer layer or strike face andcellular material between the strike face and the vehicle or vesselhull. See U.S. Pat. No. 1,266,196. See also U.S. Pat. Nos. 5,200,256 and6,698,331 and pending patent application Ser. No. 12/765,546.

Still, there is a need for specialized armor adapted for militaryamphibious vehicles. One example is the Marine Corps “ExpeditionaryFighting Vehicle” (EFV). Another example is the “Marine PersonnelCarrier” or MPC. These and other vehicles may encounter many differentcaliber rounds and armor piercing projectiles such as 7.62 mm or 14.5 mmarmor piercing type bullets or bomb fragments of various sizes.

Existing armor for such vehicles may not adequately protect the vehicleoccupants when such rounds are fired at the vehicle.

SUMMARY OF THE INVENTION

The invention provides for a new armor system configuration especiallyadapted for amphibious vehicles.

Featured is a buoyant armor for jacketed rounds comprising an outer,laminate reinforced strike face having a hardness of greater than 640Brinell and configured to strip the jacket off a round as it passesthrough the strike face and to rotate the projectile. Foam greater than40 mm thick is disposed behind the strike face and is configured todisperse the round and/or its fragments and also to provide buoyancy tothe armor.

In one example, the outer, laminate reinforced strike face is between 2and 10 mm thick, (e.g., between 3-6 mm). The preferred foam includes athicker lower density layer sandwiched between two thinner structuralfoam layers. The lower density layer may be a closed cell plastic foam.

Further included, in one embodiment is an inner, laminate reinforcedstrike face between the outer, laminate reinforced strike face and thefoam. This layer is configured to fragment a stripped round. The inner,laminate reinforced strike face is preferably thicker than the outer,laminate reinforced strike face. The inner, laminate reinforced strikeface preferably has a hardness greater than 640 Brinell, is reinforced,and is between 5-8 mm thick. In the preferred embodiment, there a spacerlayer between the inner and outer laminate reinforced strike faces madeof structural foam.

Buoyant armor in accordance with examples of the invention include anouter, laminate reinforced strike face having a hardness greater than640 Brinell and configured to strip the jacket of a projectile as itpasses through the strike face and to rotate the projectile, an inner,laminate reinforced strike face separated from the outer, laminatereinforced strike face by a spacer layer, and foam greater than 40 mm.

In one example, buoyant armor comprises an outer, laminate reinforcedstrike face having a hardness greater than 640 Brinell and a thicknessof between 2-10 mm and configured to strip the jacket of a round as itpasses through the strike face and to rotate the round. A thicker lowdensity foam layer sandwiched is between two thinner structural foamlayers behind the outer, laminate reinforced strike face. Together, thefoam layers have a thickness of greater than 40 mm and are configured todisperse the round and/or its fragments and to provide buoyancy to thearmor.

The subject invention, however, in other embodiments, need not achieveall these objectives and the claims hereof should not be limited tostructures or methods capable of achieving these objectives.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Other objects, features and advantages will occur to those skilled inthe art from the following description of a preferred embodiment and theaccompanying drawings, in which:

FIG. 1 is a schematic three dimensional view showing an example of anamphibious vehicle equipped with the buoyant armor of the invention;

FIG. 2 is a schematic three dimensional exploded view showing variouscomponents of an example of an armor plate in accordance with theinvention; and

FIG. 3 is a schematic three dimensional exploded view showing thevarious components of another example of an armor plate in accordancewith the invention.

DETAILED DESCRIPTION OF THE INVENTION

Aside from the preferred embodiment of embodiments disclosed below, thisinvention is capable of other embodiments and of being practiced orbeing carried out in various ways. Thus, it is to be understood that theinvention is not limited in its application to the details ofconstructions and the arrangements of components set forth in thefollowing description or illustrated in the drawings. If only oneembodiment is described herein, the claims hereof are not to be limitedto that embodiment. Moreover, the claims hereof are not to be readrestrictively unless there is clear and convincing evidence manifestinga certain exclusion, restriction, or disclaimer.

FIG. 1 shows amphibious vehicle 12 protected with one or more armorplates 14 bolted to metal vehicle hull 16. More or less plates may beincluded. In one preferred design, each plate 14, FIG. 2 includes 3-6 mmthick outer laminate reinforced steel strike face 20. Hard steel (650Brinell hardness) available from SSAB Swedish Steel, AB under the brandname “Armox” can be used. Outer surface 22 of strike face 20 waslaminated, for example, with a fiber reinforced composite material suchas a reinforced epoxy glass scrim to mitigate cracking of the brittlesteel when impacted by a round. The laminate reinforcement wasundertaken by Incident Control Systems, Inc. located in New Bedford,Mass., seller of “Revolution” brand armor.

Strike face 20 is thus designed to strip the jacket off a round as iteasily passes through strike face 20. Strike face 20 is also configuredto rotate the projectile, e.g., to cause it to yaw. Typically, the backor rear surface of the strike face is not reinforced. The strike face ispreferably designed to allow an armor piercing projectile to passthrough the strike face without severely damaging the strike face. Thestrike face, while reducing some of the velocity of the projectile,causes the projectile to yaw or rotate sideways so that the armorpiercing core point is now oriented at an angle as opposed to normal tothe armor plate components.

Behind strike face 20 is 12.7-38 mm spacer layer 24 (typically styreneacrylonitrile polymer structural foam). This foam material is used toprevent a reflected projectile shock wave from damaging strike face 20.Foam layer 24 also provides support to strike face 20 and creates spacesufficient for the projectile to turn or rotate. Foam layer 24 alsoprovides buoyancy to the armor system.

Inner strike face 26 is typically 3-7 mm thick and again it isreinforced with an outer laminate and is made of hard steel (650Brinell) as discussed above. Preferably, strike face 26 is the samematerial as strike face 20 but strike face 28 is thicker.

Inner strike face 26 fractures the hardened steel core of the round uponits impact with strike face 26 taking most of the energy out of theprojectile as well as significantly reducing its velocity. Strike face26 thus fragments the stripped round.

Foam is then present between inner strike face 26 and vehicle hull 16,preferably thicker low density foam layer 32 sandwiched between thinnerstructural foam layers 30 and 34. Ply 30 can be 12.7-25.4 mm styreneacrylonitrile polymer structural foam, layer 34 can be 12.7-38 mmstyrene acrylonitrile polymer structural foam, and layer 32 can be25.4-50.8 industrial polymethacrylimide closed cell plasticfoam.

The first structural foam layer 30 functions to support strike face 26.Ply 32 functions to add buoyancy and to provide a void space. Thismaterial typically has a low density and thus is very soft and prone tocracking. Ply 34 is bonded to the back of layer 32 and thus layers 32and 34 serve to reinforce low density buoyant foam ply 32.

Once projectile fragments pass through inner strike face 26, they enterfoam plies 30, 32, 34 which together increase the spall cone anddisperse the fragments onto hull plate 16.

Preferably, the aggregate specific gravity of all the layers combined isless than one g/cm³ making it positively buoyant. Particularly, it ispreferred that 40-50 mm of foam reside behind first outer hardened metalstrike face 20.

In one particular example, outer strike face 20 was 4 mm thick, foamlayer 24 was 25.4 mm thick, inner strike face 26 was 5 mm thick, foamlayer 30 was 12.7 mm thick, foam layer 32 was 25.4 mm thick, and foamlayer 34 was 25.4 mm thick. All of these layers were bonded to eachother using an adhesive. The resulting armor plate was bolted to avehicle hull 8 mm thick make of high hardness steel. Strike face 20could, however, be between 2-10 mm thick.

The technology was tested against the STANAG 4569 Level III and Level IVThreat requirements with a 14.5 mm×114 B32 Armor Piercing Projectile, a7.62 mm×51 WC Armor Piercing Projectile, and 20 mm Fragment SimulatingProjectiles at high velocities.

In another example, armor plate 14′, FIG. 3 includes outer strike face40 and foam plies 42, 44, and 46. Typically outer strike face 40includes laminate reinforced surface 41 and outer strike face 40 is 5-8mm thick. Thus strike face 40 has the same composition as strike face20, FIG. 2 but is thicker. Foam layers 42, 44, and 46 have the samecomposition as foam layers 30, 32, and 34, FIG. 2, respectively.Typically, foam layer 42 is 6.3-50.8 mm thick, foam layer 44 is12.7-50.8 mm thick, and foam layer 46 is 6.35-50.8 mm. In one particularexample, foam layer 42 was 12.7 mm thick, foam layer 44 was 50.8 mmthick, and foam layer 46 was 25.4 mm thick for an 8 mm high hardnesssteel vehicle hull 16. In total, foam greater than 40 mm thickness ispreferred.

Strike face 40 preferably has a hardness greater than 640 Brinell. Thesteel material is laminated with a reinforced epoxy glass scrim tomitigate cracking of the brittle steel as discussed above. Strike face40 is designed to allow the armor piercing projectile to pass throughthe strike face without severely damaging the strike face. When theprojectile passes through strike face 40, the projectiles jacket isstripped from the round and the hardened steel core penetrator isfractured typically with the point being completely broken apart.Additionally, strike face 40 significantly reduces the velocity of theprojectile and causes the larger remnants of the fractured core piecesto yaw or rotate sideways so that the larger core pieces are more likelyto impact hull 16 broadside.

Structural foam layer 42 is used to support steel strike face 40. Foamlayer 44 is used for buoyancy and void space. Structural foam layer 46is bonded to the back of low density buoyant foam layer 44 and togetherwith foam layer 42 reinforces and supports low density buoyant foamlayer 44.

Once the projectile fragments pass through strike face 40, they enterfoam layers 42, 44, and 46 which serve to increase the spall cone anddisperse the fragments onto hull plate 16. Again, the combined aggregatespecific gravity of the complete armor assembly is less than one g/cm³,making it positively buoyant.

A system of this configuration with an 8 mm strike face was tested on asteel hull and another system with a 6 mm strike face was tested on analuminum hull.

The result in these and other configurations is a new armor systemespecially adapted for amphibious vehicles. The armor of the subjectinvention may find uses for other vehicles and vessels, however.

Therefore, although specific features of the invention are shown in somedrawings and not in others, this is for convenience only as each featuremay be combined with any or all of the other features in accordance withthe invention. The words “including”, “comprising”, “having”, and “with”as used herein are to be interpreted broadly and comprehensively and arenot limited to any physical interconnection. Moreover, any embodimentsdisclosed in the subject application are not to be taken as the onlypossible embodiments.

In addition, any amendment presented during the prosecution of thepatent application for this patent is not a disclaimer of any claimelement presented in the application as filed: those skilled in the artcannot reasonably be expected to draft a claim that would literallyencompass all possible equivalents, many equivalents will beunforeseeable at the time of the amendment and are beyond a fairinterpretation of what is to be surrendered (if anything), the rationaleunderlying the amendment may bear no more than a tangential relation tomany equivalents, and/or there are many other reasons the applicant cannot be expected to describe certain insubstantial substitutes for anyclaim element amended.

Other embodiments will occur to those skilled in the art and are withinthe following claims.

What is claimed is:
 1. Buoyant armor for jacketed rounds comprising: anouter, laminate reinforced strike face having a hardness greater than640 Brinell and configured to strip the jacket of a projectile as itpasses through the strike face and to rotate the projectile; an inner,laminate reinforced strike face separated from the outer, laminatereinforced strike face by a spacer layer; and foam greater than 40 mmthick behind the inner strike face and configured to disperse a roundand/or its fragments and to provide buoyancy to the armor; said foamincluding a thicker lower density layer sandwiched between two thinnerstructural foam layers; and the aggregate specific gravity of all saidlayers combined being less than one g/cm³.
 2. The armor of claim 1 inwhich the outer, laminate reinforced strike face is between 2 and 10 mmthick.
 3. The armor of claim 1 in which the outer, laminate reinforcedstrike face is between 3 and 6 mm thick.
 4. The armor of claim 1 inwhich the lower density layer is a closed cell plastic foam.
 5. Thearmor of claim 1 in which the inner, laminate reinforced strike face isthicker than the outer, laminate reinforced strike face.
 6. The armor ofclaim 1 in which the inner, laminate reinforced strike face has ahardness greater than 640 Brinell.
 7. The armor of claim 1 in which theinner, laminate of strike face is between 5-8 mm thick.
 8. The armor ofclaim 1 in which the spacer layer includes structural foam.
 9. Buoyantarmor for jacketed rounds comprising: an outer, laminate reinforcedstrike face having a hardness greater than 640 Brinell and a thicknessof between 2-10 mm and configured to strip the jacket off a round as itpasses through the strike face and to rotate the round; a foam layerbehind the outer laminate reinforced strike face configured to prevent areflected projectile shock wave from damaging the outer, laminatereinforced strike face; an inner, laminate reinforced strike face behindsaid foam layer and configured to fragment the stripped round; a thickerlow density foam layer sandwiched between two thinner structural foamlayers behind the inner, laminate reinforced strike face and togetherhaving a thickness greater than 40 mm and configured to disperse theround and/or its fragments and provide buoyancy to the armor; and theaggregate specific gravity of all said layers combined being less thanone g/cm³.
 10. The armor of claim 9 in which the low density foam layeris a closed cell plastic foam.
 11. The armor of claim 9 in which theinner, laminate reinforced strike face has a hardness greater than 640Brinell.
 12. The armor of claim 9 in which the inner, laminate of strikeface is between 5-8 mm thick.